1. Field of the Invention
The invention relates to an illumination device for backlighting an image reproduction device containing light valves, wherein luminous spots formed by a plurality of light emitting diodes are in each case arranged in grid form.
2. Description of the Prior Art
Image reproduction devices having light valves, in particular liquid crystal displays, require sufficiently bright and uniform backlighting. This is achieved by means of fluorescent tubes in the case of relatively large displays, such as computer screens for example. The known illumination devices do not suffice, however, in applications requiring a very high luminance. Thus, a very high luminance is required for so-called head-up displays in motor vehicles, by way of example, since the reflected image of the display must still be visible even when there is high ambient brightness.
GB 2 361 581 shows an arrangement having a light emitting diode which is arranged in a depression of a heat-dissipating substrate. A plurality of such substrates may be arranged in grid form, a printed circuit connecting all light emitting diodes and substrates to one another. However, this arrangement is difficult to produce; in particular, connecting individual light emitting diodes in series is very difficult.